For future reference.

One place you do not want to skimp is PSU Quality.
Do not worry so much about getting the most power, but what is needed plus a little, but Quality is key.
If you only need 450W then get a good 500W, not a cheap 650W.

Always take a downgrade (not quality wise) in other parts,, slower CPU or less ram, smaller HDD, whatever.

New parts can be defective, get them replaced ASAP and do not use them, Especially a PSU. Power is a funny thing and can reek havoc on a PC in very short order, or cause problems that may appear to be from other hardware. Lesson here,, don't skimp on PSU, and don't take them for granted.

I know I am reitterating what has already been posted for the most part, but just want to drive the point home.

And last but not least,,, almost all good new PSU's should come with a new power cable.
Always, Always and forever, use it, when replacing the PSU. Do not continue using the old one. Even if the old PSU was working.

**if it is a cheap junk PC that you are not worried about or giving away, then you can skimp on the PSU**